In the nonfiction market, the top-selling books remain how-to, self-help, motivational, and inspirational/religious. These also represent the books that ghostwriters are most frequently asked to write.
I've written widely on all of these topics and am familiar with the style, organization, and content used in the ever-growing self-help movement. If you have a revolutionary idea (or a new take on an old theme) that fits this category, I can write a book that will put your concept into the literary marketplace--and beyond.
In terms of fiction, mystery, romance, and thrillers are the top sellers online and at bookstores. I'm skilled at writing all genre fiction, including these three categories.
See also Topics Considered.